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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6994d8832fcf287b3ffb7d63cf47e0bfa4a7d401e7b800a3cc001c9d6019a37' 
  AND token = 'dQ/VRWlFsQIPsHqkmqslJYNrrAskn25nrbkSwM66qYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}